1. Field of the Invention
The present invention relates to a confocal microscope apparatus for obtaining an image of a measuring object at a predetermined depth. More specifically, the present invention relates to a confocal microscope apparatus for obtaining an image of a measuring object at a predetermined depth using OCT (optical coherence tomography) measuring.
2. Description of the Related Art
It is known that confocal microscope apparatuses are used for performing endoscopic examinations of the inside of human bodies. One such apparatus that employs the principle of OCT measuring using heterodyne detection and the principle of confocal microscope is proposed as described, for example, in U.S. Pat. No. 6,151,127. In the confocal microscope apparatus disclosed in U.S. Pat. No. 6,151,127, laser light outputted from the light source is split into measuring light and reference light, and the reference light is inputted to a reference mirror that moves in the optical axis directions, thereby the frequency of the reference light is modulated.
In the mean time, the measuring light is guided to the measuring object using an optical fiber, and the measuring light outputted from the optical fiber is focused on the measuring object by a condenser lens. Here, the measuring light output section of the optical fiber and the focal position on the measuring object are in confocal relationship, thereby the reflected light reflected from the measuring object other than the focal position is prevented from entering the optical fiber.
Thereafter, the interference light between frequency-modulated reference light and the reflected light reflected from the measuring object guided by the optical fiber is heterodyne detected, and the reflection information from the focal position is obtained. By moving the focal position of the condenser lens in the directions orthogonal to the depth direction of the measuring object, a tomographic image of the object at a predetermined depth is obtained.
Here, when performing the heterodyne detection, it is necessary to move or vibrate the reference mirror to differentiate the frequency between the measuring light and reference light. When the reference mirror is moved or vibrated, however, the heterodyne detection is also performed for the measuring object in the depth direction. Consequently, when obtaining a tomographic image at a predetermined depth as in the confocal microscope apparatus described above, the interference light is not detectable unless the optical path length of the reference light corresponds to the optical path length of the measuring light to the focal position of the condenser lens when the reference mirror is moved. This causes a problem of time redundancy when obtaining a tomographic image.
In view of the circumstances described above, it is an object of the present invention to provide a confocal microscope apparatus capable of rapidly obtaining a tomographic image using OCT measuring.